The invention relates to an additive for improving the properties of heavy oils and to heavy oils containing this additive.
Heavy oils are obtained in the processing of petroleum types (crude oils) and are residues of processing operations such as distillation and atmospheric pressure or reduced pressure, thermal or catalytic cracking and the like. From the chemical viewpoint, these residual furnace fuels or residual engine fuels (bunker C oils) essentially comprise paraffinic, naphthenic and aromatic hydrocarbons, some of high molecular weight. The high molecular weight components, also termed asphaltenes, are not present in dissolved form, but in a more or less dispersed form, which gives rise to numerous problems. Thus, asphaltenes and likewise other poorly soluble or insoluble compounds (for example oxygen compounds, nitrogen compounds and sulfur compounds) and products of ageing, in the absence of effective dispersants, separate out from the oil phase, forming an extremely undesirable two-phase system. In the presence of water, or even only moisture, in addition, sludge formation can occur. All these higher-molecular weight compounds and contents in the heavy oil, in addition, adversely affect the oil combustion process, for example owing to intensified soot formation.
Heavy oils, in particular in the form of heavy fuel oils (Marine Fuel Oils) and of mixtures of heavy fuel oils and heavy distillates (Inter Fuel Oils) are used in large amounts, primarily as furnace fuel in industrial plants and power stations and as engine fuel for relatively slow-burning internal combustion engines, in particular marine engines. In the prior art, therefore, numerous proposals have already been made for additives which are intended to exclude the disadvantageous properties described of the heavy furnace fuel oils and engine fuel oils, that is, in particular, the formation of two phases by asphaltenes and other higher-molecular weight fractions, sludge formation and the impairment of combustion.
Thus, FR-A-2 172 797 describes basic iron salts of organic acids and FR-A-2 632 966 describes a mixture of iron hydroxide and a basic calcium soap as auxiliaries to enhance the combustion of heavy oils. U.S. Pat. No. 4,129,589 recommends highly basic and oil-soluble magnesium salts of sulfonic acids as oil additives. The more recent publication EP-A-476 196 describes, as oil additive, a mixture essentially comprising (1) at least one oil-soluble carbonyl manganese compound, (2) at least one oil-soluble neutral or basic alkali metal salt or alkaline earth metal salt of an organic acid component and (3) at least one oil-soluble dispersant selected from the group consisting of the succinimides. In addition, mention may also be made of U.S. Pat. No. 5,421,993, which describes alkoxylated fatty amines and fatty amine derivatives as corrosion inhibitors, demulsifiers and pour point depressants for crude oils.
It has now been found that the combination of alkoxylated fatty amine compounds and organic metal salts is a particularly effective additive for heavy oils, in particular with regard to emulsifying and/or dispersing asphaltenes, sludge and the like and also with regard to improving oil combustion.
The additive according to the invention essentially comprises
a) 1 to 99% by weight, preferably 20 to 80% by weight, and in particular 40 to 60% by weight, of at least one amine compound of the formula (I) below 
xe2x80x83in which
n is 1, 2, 3 or 4,
A is a radical of the formulae (II) to (V) 
where R is a C6 to C22 alkyl, preferably a C6 to C18 alkyl, and m is 2, 3 or 4, preferably 2 or 3,
x is a number from 5 to 120, preferably 10 to 80,
R1 is H, CH3 or H and CH3, where the oxyalkylene radicals are arranged randomly or in blocks, and
b) 1 to 99% by weight, preferably 20 to 80% by weight, and in particular 40 to 60% by weight, of at least one oil-soluble or oil-dispersible neutral or basic metal salt compound containing a metal of the first main group of the Periodic Table of the Elements, of the second main group, of the first subgroup, of the second subgroup, of the fourth subgroup, of the sixth subgroup, of the eighth subgroup or of the lanthanide group (rare earth metals) of the Periodic Table of the Elements and a carboxylic acid, sulfonic acid, acid ester of phosphoric acid or acid ester of sulfuric acid containing a hydrocarbon radical of in each case 8 to 40 carbon atoms, preferably 12 to 30 carbon atoms, as acid component, percentages by weight based on the additive.
Component a) of the additives according to the invention is an amine compound in accordance with formula (I). These alkoxylated fatty amines and fatty amine derivatives are prepared by conventional alkoxylation methods, by reacting an amine in accordance with radical A in formula (I) with x mol of ethylene oxide alone (R1 is H and the polyoxyalkylene radical comprises ethylene oxide units) or with x mol of propylene oxide alone (R1 is CH3 and the polyoxyalkylene radical comprises propylene oxide units) or with x mol of ethylene oxide and propylene oxide simultaneously or in succession (R1 is H and CH3 and the polyoxyalkylene radical comprises ethylene oxide and propylene oxide units which are present in a random distribution or in blocks). The reaction is generally carried out at a temperature of 100 to 180xc2x0 C. in the presence or absence of an alkali or acid alkoxylation catalyst in the absence of air. Preferred amine compounds as component a) correspond to the formula (VI) below 
xe2x80x83in which
The amine compounds of the formula (VI) and their preparation are described extensively in U.S. Pat. No. 5,421,993 mentioned at the outset, which is herein incorporated by reference. They are obtained by alkoxylation of amines of the specified formula (II) to (V), initially with ethylene oxide, and then with propylene oxide, with addition of bases such as alkali metal hydroxides. The reaction is performed in stages at a temperature of preferably 100 to 160xc2x0 C. The amount of catalyst/base used is generally 0.5 to 3.0% by weight, based on the starting amine used. The molar amount of ethylene oxide and propylene oxide per mol of starting amine corresponds to the specified values of a and b and the values of c. In detail, reference is made to said U.S. Pat. No. 5,421,993. The following summary gives examples of suitable amine compounds (a1 to a6) according to Formula (I) as component a):
Preferred metals in the metal salt compound of the component b) are the alkali metals or alkaline earth metals (first and second main group of the Periodic Table of the Elements), copper or silver (first subgroup), zinc or cadmium (second subgroup), titanium or zirconium (fourth subgroup), molybdenum, chromium or tungsten (sixth subgroup), iron, cobalt or nickel (eighth subgroup) and lanthan, cerium or ytterbium (lanthanide group). Particularly preferred metals are the alkaline earth metals, such as barium, beryllium, calcium or magnesium, copper, zinc, zirconium, molybdenum, iron, nickel, cerium or ytterbium.
Preferred acids in the metal salt compound of the component b) are aliphatic carboxylic acids having 8 to 40 carbon atoms, preferably 12 to 30 carbon atoms. The aliphatic radical can be unbranched or branched, saturated or unsaturated. The aliphatic carboxylic acids are preferably fatty acids having 8 to 40 carbon atoms, preferably 12 to 30 carbon atoms. The aliphatic carboxylic acids and fatty acids can be of synthetic or natural type, and they can be present as such or as a mixture of two or more acids. Examples which may be mentioned are octanoic acid (caprylic acid), decanoic acid (capric acid), dodecanoic acid (lauric acid), tetradecanoic acid (myristic acid), hexadecanoic acid (palmitic acid), octadecanoic acid (stearic acid), eicosanoic acid (arachic acid), docosanoic acid (behenic acid), dodecenoic acid (lauroleic acid), tetradecenoic acid (myristoleic acid), hexadecenoic acid (palmitoleic acid), octadecenoic acid (oleic acid), 12-hydroxyoctadecenoic acid (ricinoleic acid), octadecadienoic acid (linoleic acid) and octadecatrienoic acid (linolenic acid), as well as coconut fatty acid, tallow fatty acid, palm kernel fatty acid and the like.
In addition to said (simple) fatty acids, dimeric fatty acids are also preferred acid components. These dimeric fatty acids correspond to the formula (VII)
HOOCxe2x80x94R2xe2x80x94COOHxe2x80x83xe2x80x83(VII)
in which R2 is a divalent hydrocarbon radical having 34 carbon atoms (R2 is therefore the radical which contains 34 carbon atoms and is formed in the dimerization of an unsaturated fatty acid containing 18 carbon atoms to give a dicarboxylic acid having a total of 36 carbon atoms).
As is known, they are prepared by dimerizing unsaturated C18 fatty acids, for example oleic acid, linoleic acid, linolenic acid or tallow fatty acid (dimerization is taken to mean combining two identical molecules to form one new molecule, the dimer, by addition reaction). C18 fatty acids are generally dimerized at a temperature of 150 to 250xc2x0 C., preferably 180 to 230xc2x0 C., with or without a dimerization catalyst. The resulting dicarboxylic acid (that is the dimeric fatty acid) corresponds to the formula VII given, where R2 is the divalent connection member which is formed in the dimerization of the C18 fatty acid, bears the two xe2x80x94COOH groups and has 34 carbon atoms. R2 is preferably an acyclic (aliphatic) or a monocyclic or bicyclic (cycloaliphatic) radical having 34 carbon atoms. The acyclic radical is generally a branched (substituted) and monounsaturated to triunsaturated alkyl radical having 34 carbon atoms. The cycloaliphatic radical generally likewise has 1 to 3 double bonds. The preferred dimeric fatty acids described are generally a mixture of two or more dicarboxylic acids of the formula VII having structurally different R2 radicals. The dicarboxylic acid mixture frequently has a greater or lesser content of trimeric fatty acids, which were formed in the dimerization and were not removed in the product work-up by distillation. Similar mixtures are obtained from natural products, for example in the production of colophony from pine extract. Below, some dimeric fatty acids may be specified as formulae, in which the hydrocarbon radical bearing the two xe2x80x94COOH groups is an acyclic, monocyclic or bicyclic radical: 
The dimeric fatty acids described are commercially available under the name xe2x80x9cdimerized fatty acidsxe2x80x9d, or xe2x80x9cdimeric fatty acidsxe2x80x9d and, as already mentioned above, can have a greater or lesser content of trimerized fatty acids.
Preferred acids in the metal salt compound of the component b) are, furthermore, aliphatic or aromatic sulfonic acids having 8 to 40 carbon atoms, preferably 12 to 30 carbon atoms, in the aliphatic or aromatic radical. Here also, the aliphatic radical can be unbranched or branched, saturated or unsaturated. The aromatic sulfonic acid is preferably a benzene sulfonic acid having an alkyl or alkenyl radical containing 12 to 30 carbon atoms. Among said representatives, the metal soaps are particularly preferred as component b).
The organic metal salt to be used according to the invention as component b) can be prepared by the methods described in the prior art. Reference may be made in this case in particular to the publications mentioned at the outset FR-A-2 172 797, FR-A-2 632 966, U.S. Pat. No. 4,129,589 and EP-A-476 196, which are incorporated herein. The organic metal salts to be used according to the invention shall be oil-soluble or at least oil-dispersible. In addition, these relate to a neutral or basic product, the latter being preferred. The expression xe2x80x9cbasicxe2x80x9d, as is known, describes metal salts in which the metal is present in a higher stoichiometric amount than the organic acid radical. The basic metal salt products to be used according to the invention therefore have a pH of generally 7.5 to 12, preferably from 8 to 10.
The additive according to the invention is prepared by mixing together the components a) and b), with or without the use of a solvent or dispersion medium. Suitable solvents or dispersion media of this type are lower or higher alcohols such as ethanol, isopropanol, butanol, decanol, dodecanol and the like, lower or higher glycols and their monoalkyl or dialkyl ethers such as ethylene glycol, propylene glycol, diethylene glycol, tetra-ethylene glycol, tetrapropylene glycol and the like, low-to medium-boiling aliphatic, aromatic or cycloaliphatic hydrocarbons such as toluene, xylene, naphtha and the like, light to medium-heavy mineral oils, oil distillates, natural or synthetic ails and derivatives thereof and mixtures of two or more of these solvents. The two components, amine compound and metal salt compound, are generally brought together at atmospheric pressure and at a temperature of 15 to 100xc2x0 C., preferably 20 to 70xc2x0 C.
The heavy oils according to the invention feature a content of the additive described. The active amount of additive in the heavy oil can vary. within broad limits. Generally, the oil contains 2 to 2000 ppm of additive, preferably 100 to 1000 ppm.
The additive according to the invention and the heavy oils containing this additive have a property profile which is particularly desired, and this could be primarily due to an unexpectedly high synergy of the combination according to the invention of the components a) and b). Thus the additive is present in the oil in dissolved or highly dispersed form. Even in oils having a high content of asphaltenes and/or other higher-molecular weight compounds, all these insoluble fractions are highly emulsified or dispersed. The same also applies in the case of sludges, so that sludge formation is also largely excluded or at least markedly decreased. The additive according to the invention, moreover, is a highly effective combustion enhancer. It ensures the complete combustion of heavy oils with simultaneous decrease in soot formation. The heavy oils according to the invention therefore comply to a surprisingly great degree with the requirements mentioned at the outset. As a result of said actions, the additive according to the invention leads to oils which, furthermore, also have in particular the following advantageous properties: improved storage stability (reduced sedimentation of insoluble cons tituents), improved pumpability owing to low viscosity, longer operating life of the filter system, improved injection behavior at the combustion devices, which additionally contribute to optimizing the combustion, and increased corrosion protection for all devices owing to the high inhibition of corrosion by the additive. The heavy oils according to the invention are therefore primarily used as furnace fuel for industrial plants and power stations and likewise as engine fuel for marine engines.